This invention relates to dynamoelectric machines and more particularly, to an induction motor having a rotor shaft and a fan which is installable on the shaft in a more cost efficient way. While the invention is disclosed in particular detail with respect to such application, those skilled in the art will recognize the wider applicability of the invention disclosed hereinafter.
In order to operate properly and have a long service life, it is important for dynamoelectric machines such as electric motors to operate within a certain temperature range. That is to say, physical properties of wire insulation, bearing lubricant material, and overall electrical performance of the motor all are adversely effected by high temperature operations. The problem can become particularly troublesome when the motor operates in enclosed environments, such as domestic appliances, in the form of dishwashers, for example. In the past, the methods employed to solve the problem involved relatively high cost construction techniques for the motor design. One way to reduce temperature is to attach a fan on a motor shaft with the fan moving sufficient air through the motor to keep it cool. Usually, prior art designs employed a shaft having a flat or keyway formed in it. The fan is designed for attachment to the flat or keyway portion of the shaft. However, there is a cost associated with manufacturing and assembling a stepped shaft having flats or keyways for a motor and the fan used with such a shaft. It would be advantageous if a non-stepped, lower cost shaft could be used in the motor. However, prior art motor fans, are not designed for installation on such shafts.